Method of controlling the temperature of a partial oxidation burner

Abstract

The temperature of a burner in the reaction zone of a partial oxidation gas generator is controlled so that there is substantially no condensation of H 2 O from the hot raw product gas on the surface of the burner. Burner corrosion is thereby reduced. In the method, burner coolant is introduced into the burner at a pressure greater than that in the reaction zone and at a temperature in the range of about 5° to 50° F. higher than the dew point of the raw product gas contacting the burner in the reaction zone. The heated water coolant leaving the burner flows to a pressurized receiving vessel and its temperature is reduced by expansion into a feed vessel. Saturated steam is produced from a portion of the flashed water and is separated in the feed vessel for use as a heat source. Steam condensate is thereby produced and recycled to the feed vessel as make-up. The cooled liquid water coolant is then pumped into the inlet to the burner at a higher pressure than that in the feed vessel. This prevents raw product gas from leaking out of the gas generator by way of any break in the burner cooling water system. In another embodiment, the temperature of the heated water coolant leaving the burner is reduced by direct heat exchange with cooler make-up water.

I claim: 
     
       1. A method for controlling the temperature of a burner in a free-flow reaction zone of a gas generator for the partial oxidation of a gaseous hydrocarbon fuel, liquid hydrocarbonaceous fuel, or a slurry of solid carbonaceous fuel with a free-oxygen containing gas and optionally in the presence of a temperature moderator to produce in said reaction zone a hot raw gas stream substantially comprising H 2 , CO, CO 2 , H 2  O, H 2  S, COS, CH 4 , Ar and N 2 , said burner being equipped with cooling means and liquid water coolant inlet and outlet lines connected to said cooling means comprising: (1) continuously removing from the cooling means of said burner by way of said outlet line a stream of heated liquid water coolant that was heated by indirect heat exchange with said hot raw gas stream contacting the outside surface of that portion of said burner within said reaction zone, and simultaneously introducing into said cooling means by way of said coolant inlet line a stream of liquid water coolant from (6); wherein substantially no H 2  O from said raw gas stream condenses on the external surfaces of that portion of said burner contained within said reaction zone;   (2) introducing said heated liquid water coolant from (1) into a receiving pressure vessel where the pressure is maintained above that in said reaction zone;   (3) passing a stream of water coolant from said receiving vessel into a cooling water feed pressure vessel;   (4) maintaining the pressure in said feed vessel below the pressure in said receiving vessel;   (5) removing saturated steam from said feed vessel at the saturation temperature corresponding to the pressure in the feed vessel, wherein said saturation temperature is above the dew point of said hot raw gas mixture;   (6) removing a stream of liquid water coolant from said feed vessel, increasing the pressure of said stream of coolant to above the pressure in the reaction zone, and introducing said stream of liquid water coolant into the burner inlet line as provided in (1) at a temperature in the range of about 5° F. to 50° F. above the dew point of said hot raw gas mixture in the reaction zone; and including the steps of either   (7) mixing a stream of make-up water at a lower temperature with the heated liquid water coolant from the burner being introduced into the receiving vessel in (2) either prior to or within the receiving vessel thereby cooling the stream of heated liquid water coolant by direct heat exchange and forming a water coolant mixture, passing said water coolant mixture from said receiving vessel into said cooling water feed pressure vessel as provided in (3), wherein the temperature of the water coolant in said receiving and feed vessel is substantially the same, and removing a separate stream of liquid water coolant from the feed vessel; or   (8) passing said stream of water coolant from said receiving vessel to said feed vessel as provided in (3) by way of an expansion means thereby converting a portion of said water into steam at a lower temperature prior to introducing said mixture of water and steam into the feed vessel at said lower temperature, and introducing into said feed vessel a stream of make-up water at substantially the same temperature as the temperature of the water in said feed vessel.   
     
     
       2. The method of claim 1 provided with the step of introducing at least a portion of the steam from (5) into said gas generator as at least a portion of said temperature moderator. 
     
     
       3. The method of claim 1 provided with the step of using at least a portion of the steam from (5) to preheat at least one feedstream to the gas generator while producing condensate. 
     
     
       4. The method of claim 3 provided with the step of introducing at least a portion of said condensate into said feed vessel as the make-up water in (8). 
     
     
       5. The method of claim 1 provided with the step of removing said heated cooling water from the cooling means in (1) at a temperature in the range of about 5.0° to 30° F. greater than the temperature of the liquid water coolant entering said burner. 
     
     
       6. The method of claim 1 provided with the step of removing said heated cooling water from the cooling means in (1) at a pressure which is about 50 to 200 psi above the pressure of the reaction zone of the gas generator. 
     
     
       7. The method of claim 1 provided with the step of maintaining the level of the liquid coolant in the receiving and feed vessels so that the vessels are filled to about 50-80% of their volumes. 
     
     
       8. The method of claim 1 wherein said expansion means is a flashing control valve. 
     
     
       9. A continuous method for reducing the temperature of a liquid coolant for a burner firing downwardly into a free-flow reaction zone of a gas generator for the partial oxidation of a gaseous hydrocarbon fuel, liquid hydrocarbonaceous fuel, or a slurry of solid carbonaceous fuel with a free-oxygen containing gas and optionally in the presence of a temperature moderator at a temperature in the range of about 1700° to 3000° F. and a pressure in the range of about 1 to 250 atmospheres to produce a raw gas stream substantially comprising H 2 , CO, CO 2 , H 2  O, H 2  S, COS, CH 4 , Ar, and N 2  while preventing the condensation of H 2  O from said raw gas stream on the cooled external surfaces of said burner comprising: (1) removing from said burner a stream of heated burner cooling water which was heated by indirect heat exchange with said raw gas stream to a temperature which is in the range of about 10° F. to 80° F. greater than the dew point temperature of said raw gas stream in the reaction zone and at a pressure which is about 50 psi to 200 psi higher than the pressure in the gas generator;   (2) introducing the heated burner cooling water from (1) into a water receiving vessel;   (3) maintaining the water pressure in said water receiving vessel at a pressure above the gasifier pressure,   (4) passing water from said water receiving vessel through an isenthalpic expansion means thereby reducing its pressure and simultaneously converting at least a portion of said water into steam while cooling the remainer of said water about 5° F. to 30° F. below the temperature of the water in said receiving vessel and about 5° F. to 50° F. above the dew point temperature of the raw gas stream in the reaction zone;   (5) introducing the cooled water and steam from (4) into a water feed vessel;   (6) introducing make-up water into said water feed vessel at substantially the same temperature as the water in said feed vessel;   (7) removing saturated steam from said water feed vessel at the saturation temperature corresponding to the pressure in the feed vessel wherein said saturation temperature is about 5° F. to 50° F. above the dew point of the hot raw gas stream in contact with the outside of the burner in the reaction zone; and   (8) increasing the pressure of at least a portion of the cooled water from said water feed vessel to a pressure which is about 80 psi to 400 psi greater than the pressure in said reaction zone, and introducing at least a portion of said cooled and pressurized water into said burner as a coolant at a temperature of about 5° F. to 50° F. above the dew point temperature of the raw gas stream in the reaction zone.   
     
     
       10. The method of claim 9 provided with the step of introducing at least a portion of the steam from (7) into said gas generator as at least a portion of said temperature moderator. 
     
     
       11. The method of claim 9 with the step of preheating at least one feedstream to the gas generator while producing condensate by indirect heat exchange with at least a portion of the steam from (7). 
     
     
       12. The method of claim 11 provided with the step of introducing at least a portion of said condensate into said water feed vessel as the make-up water in (6). 
     
     
       13. The method of claim 9 provided with the step of introducing nitrogen gas into said water receiving vessel to pressurize said vessel. 
     
     
       14. The method of claim 9 wherein said isenthalpic expansion means is a isenthalpic flashing control valve. 
     
     
       15. A continuous method for reducing the temperature of a liquid coolant for a burner firing downwardly into a free-flow reaction zone of a gas generator for the partial oxidation of a gaseous hydrocarbon fuel, liquid hydrocarbonaceous fuel, or a slurry of solid carbonaceous fuel with a free-oxygen containing gas and optionally in the presence of a temperature moderator to produce a raw gas stream substantially comprising H 2 , CO, CO 2 , H 2  O, H 2  S, COS, CH 4 , Ar, and N 2  while preventing the condensation of H 2  O from said raw gas stream on the cooled external surfaces of said burner comprising: (1) removing from said burner a stream of heated burner cooling water which was heated by indirect heat exchange with said raw gas stream to a temperature which is in the range of about 10° F. to 80° F. greater than the dew point temperature of said raw gas stream in the reaction zone and at a pressure which is about 50 psi to 200 psi higher than pressure in the gas generator;   (2) introducing the heated burner cooling water from (1) into a water receiving vessel;   (3) mixing a stream of make-up water at a lower temperature in the range of about ambient to 200° F. with the heated water coolant from the burner either prior to or within the receiving vessel thereby cooling the stream of heated liquid water coolant by direct heat exchange to a temperature of about 5° to 50° F. above the dew point of the raw product gas in the reaction zone;   (4) maintaining the water pressure in said water receiving vessel at a pressure of about 25 to 150 psi above the gasifier pressure;   (5) passing water from said water receiving vessel through a liquid level control means and into a water feed vessel; wherein the temperature of the liquid water coolant in the receiving and feed vessels is substantially the same;   (6) removing a separate stream of liquid water coolant from the feed vessel;   (7) removing saturated steam from said feed vessel at the saturation temperature corresponding to the pressure in the feed vessel, wherein said saturation temperature is above the dew point of the hot raw gas stream in contact with the outside of the burner in the reaction zone; and   (8) increasing the pressure of at least a portion of the cooled water from said water feed vessel to a pressure which is greater than the pressure in said reaction zone, and introducing at least a portion of said cooled and pressurized water into said burner as a coolant at a temperature of about 5°. to 50° F. above the dew point temperature of the raw gas stream in the reaction zone.   
     
     
       16. The method of claim 15 provided with the step of introducing at least a portion of the steam from (7) into said gas generator as at least a portion of said temperature moderator. 
     
     
       17. The method of claim 15 with the step of preheating at least one feedstream to the gas generator while producing condensate by indirect heat exchange with at least a portion of the steam from (7). 
     
     
       18. The method of claim 17 with the step of introducing at least a portion of said condensate into said receiving vessel as the make-up water in (3). 
     
     
       19. The method of claim 15 with the step of removing the heated cooling water from the burner in (1) at a temperature in the range of about 10° F. to 80° F. greater than the dew point of the raw gas stream in the reaction zone. 
     
     
       20. The method claim 15 with the step of introducing nitrogen gas into said water receiving vessel to pressurize said vessel.